{
  //ts类型:boolean类型
  let boo1: boolean = true;
  boo1 = false

  //ts类型:number类型
  let num1: number = 1;
  num1 = 2;

  //ts类型:string
  let str: string = "abc";
  str = "bcd";

  //ts类型:null和undefined
  let a: null = null;
  let b: undefined = undefined;


  //ts类型:bigint(编译的时候可能会报错,因为是es2020的规范,ts默认配置的支持规范小于es2020)
  let num2: bigint = 1n;

  //ts类型:symbol
  let sy1: symbol = Symbol();
}
